The interrupt delivery part is something that has been necessary for years, because X still can't give you any way to syncronize to VBL interrupts (except OpenGL).
On the other hand, I don't feel too happy with user land directly accessing IO ports. This is still dangerous, and buggy X drivers often can hang the machine, too. Memory mapped IO pages should be ok, given that the kernel would allow to map the PCI memory per device, not from /dev/mem. I suggets to keep the IO port part of a device driver inside kernel space. p>
Copyright © 2017, Eklektix, Inc.
Comments and public postings are copyrighted by their creators.
Linux is a registered trademark of Linus Torvalds